ENERGETIC AND EXERGETIC STUDIES OF MODIFIED CO_2 TRANSCRITICAL REFRIGERATION CYCLES

摘要

Modified transcritical CO_2 cycles incorporating an internal heat exchanger, vortex tube and expansion turbine, individually, are thermodynamically analyzed using Engineering Equation Solver (EES). Contours are developed to predict the optimum COP and II law efficiency at various evaporator and gas cooler exit temperatures. It is observed that expansion turbine brings the significant COP improvement of the order of 25 % while COP improvement is relatively low with vortex tube and with IHE. However, all three modifications result in decrease in optimum discharge pressure. The exergetic efficiency with work recovery turbine is found to be the best.